Snow Skiing and Snowboarding Musculoskeletal Injuries

1. Snow Skiing and Snowboarding Musculoskeletal Injuries Matthew McNairy MD 5/22/2008

2. Incidence of Skiing Injuries • 10,000 skiers in U.S. in 1935. 15 million in 2000 (200 million worldwide) • Alpine skier injury rate 2-4.4 per 1000 skier days (down from 5-8/1000 before 1975) • Injury rate in children 59% higher than in adults • Beginners at greater risk for injury (skiers and snowboarders)

3. Boots • Decreased injury rate related to decrease in ankle fractures (down 91%) and other injuries distal to the knee related to modern boots with high, rigid shell • 1980s to 1990s adult ACL injury rate increased 280%, tibial plateau injury rate increased 485%

4. Medial Collateral Ligament Injury • 20-25% of all skiing injuries, especially among beginners and intermediate skiers • Forced genu valgus: falling from “snowplow” or catching an edge with the ski suddenly tracking laterally

5. Medial Collateral Ligament Injury • MRI helpful to Diagnose displaced tears Identify associated injuries (ligamentous, meniscal or osteochondral injuries) • MRI grading I edema around ligament II partial tear III complete tear • Treatment Hinged knee brace for isolated injury Associated injuries may require surgery

6. 72 year old woman with skiing injury Grade III MCL injury

7. Anterior Cruciate Ligament Injury • 200,000 new ACL injuries/year in U.S. • 20,000 related to skiing • 13-19% of all skiing injuries

8. Anterior Cruciate Ligament • Primary restraint to anterior displacement of the tibia (Anterior tibial displacement primary cause of isolated ACL injury) • Secondary restraint to tibial rotation particularly internal rotation in full extension • Minor secondary restraint to varus-valgus angulation in full extension

9. ACL injury mechanisms Phantom boot mechanism • Deep knee flexion and internal tibial rotation • Backward fall between the skis with deeply flexed knees and weight on inner edge of the downhill ski • Sharp inward turn of ski tip • Tail of ski and stiff boot act as lever applying twisting force to knee

10. ACL injury mechanisms Boot-induced mechanism • Land after a jump on the tail of the ski, forcing the back of the boot against the calf, forcing the tibia anteriorly • May be combined with forcible quadriceps contraction

11. Bucket handle tear Lateral meniscus “Double delta” Bucket handle tear medial meniscus “Double PCL” ACL tear Quadruple cruciate sign “Jack and Jill lesion”

12. ACL injury mechanisms Aggressive quadriceps contraction • Produces anterior tibial translation through patellar tendon • Experts with powerful quads • “Falling back” position trying to regain control

13. ACL injury mechanisms Valgus-external rotation • Catching inside edge and falling forward between skis • AMRI MCL, POL medial meniscus (O’Donohue triad)

14. ACL injury mechanisms Valgus-external rotation • Catching inside edge and falling forward between skis • AMRI MCL, POL Medial meniscus (O’Donohue triad)

15. ACL injury mechanisms Varus-internal rotation • Downhill ski catches an edge, skiier falls over it • ALRI lateral ligaments lateral meniscus +/- Segond frx

17. ACL tear distribution • Proximal 1/3 of ACL 80% • Middle 1/3 17% • Distal 1/3 3%

18. Anterior Cruciate Ligament Injury • Physical exam 62-100% sensitive 56-100% specific • MRI 90-98% sensitive 90-100% specific Accuracy decreased for partial thickness or chronic tears Helpful to identify displaced tears, associated injuries

19. Injuries associated with ACL tear 60 acute complete ACL tears in skiers • 98% bone contusions • 60% posterior soft tissue injuries (posterolateral capsule, popliteus) • 50% MCL • 35% medial meniscal tear • 18% partial PCL tear • 17% LCL • 15% lateral meniscal tear • 3% Segond fracture

20. 72 year old woman with skiing injury

21. Injuries associated with ACL tear 328 acute ACL tears in skiers • 23% meniscal tear (13% lateral, 10% medial) Usual incidence of meniscal tear in acute ACL injury 60-70% (60% lateral, 40% medial)

22. ACL deficient knee • 6 times more likely to have a recurrent skiing injury • Recurrent skiing injury more severe

23. Skier’s thumb • Acute injury of the ulnar collateral ligament of the MCP joint of the thumb • AKA gamekeeper’s thumb • Most common upper extremity injury in skiing • 35-80% of upper extremity skiing injuries • 8-17% of all skiing injuries

24. Skier’s thumb mechanism • Fall with pole in outstretched hand • Pole handle acts as a fulcrum at the base of the thumb, resulting in hyperabduction and extension • Molded, strapless grips do not change frequency of injury • Should ski without straps and release the pole during fall before hit ground

25. Skier’s thumb • Clinical presentation acute UCL injury – pain, swelling, ecchymosis • Small, tender lump on ulnar aspect of MCP joint of thumb highly suggestive of Stener lesion, but lack of lump doesn’t rule it out

26. Skier’s thumb • Normal radiographs versus small avulsion fracture • Valgus stress radiographs (contraindicated if large intra-articular fracture, fracture of shaft of MC or proximal phalanx of thumb, ?small avulsion fracture) • Complete rupture of UCL likely if radial deviation at the MCP joint > 30-35 degrees or 10 degrees > opposite side

27. Avulsion fractures Cases courtesy of Tudor Hughes

28. Skier’s thumb • Partial thickness, nondisplaced complete tear, or displaced complete tear (Stener lesion – in up to 80% of complete tears) • Distal tear 5x > proximal tear > midsubstance tear

29. Stener Lesion • Complete distal or midsubstance tear • Torn UCL displaced superficial to the proximal adductor pollicus aponeurosis • Displaced UCL will not heal effectively unless normal anatomy is restored • Surgery helps to prevent complications of chronic UCL instability (pain with pinch and grasp maneuvers) • ‘Yo-yo on a string’ = proximal margin of the adductor aponeurosis abutting the folded UCL

30. Ulnar collateral ligament anatomy A Proper collateral ligament Metatarsal head to volar aspect of the phalanx Taut in flexion B Accessory collateral ligament Volar to proper ligament and attaches to the volar plate Lax in flexion C Volar plate On MRI UCL = band of low SI closely apposed to medial joint margin along its entire course

31. Adductor aponeurosis Adductor pollicis =UCL Adductor aponeurosis Adductor pollicis muscle =UCL

32. Partial tear proximal UCL

33. Complete distal UCL tear Nondisplaced Case courtesy of Tudor Hughes

34. Stener lesion “yo-yo on a string” Case courtesy of Tudor Hughes

35. Skier’s thumb treatment • Primary indications for surgery: symptomatic patient with instability (>35 degrees of angulation with stress testing) and a displaced UCL tear or displaced avulsion fracture • Displaced tear = torn fibers balled up, folded ulnarward away from joint, or gap >/= 3mm • Surgery best within 3 weeks of injury • After 1-2 months atrophy and fibrosis of UCL may preclude primary repair and require UCL reconstruction or MCP arthrodesis

36. Skiing 4-11% of all injuries #1 Rotator cuff injury (24%) #2 Glenohumeral dislocation (22%) #3 AC separation (20%) #4 Clavicle fracture (11%) Snowboarding 8-16% of all injuries #1 AC separation (32%) #2 Fracture (29%) clavicle most common #3 Glenohumeral dislocation (20%) Shoulder injuries

37. 65 year old skier Subscapularis tendon tear

38. 54 year old skier HAGL Greater tuberosity fracture

39. Snowboarding injuries • Fastest growing winter sport in the U.S. • 6.3 million active snowboarders

40. Snowboarding injuries • Lower extremity • Both feet firmly attached to board (less twisting of legs/knees) • Snowboard shorter than skis (shorter lever arm) • Usually softer boots (less ankle protection, less force transmitted to knee) • Less ACL, more ankle injuries

41. Snowboarding injuries • Upper extremity injuries • No poles • Feet perpendicular to direction of movement • Can’t stabilize by moving leg out • Fall backward (heel side) or forward (toe side) without poles to break fall • Wrist and shoulder injuries instead of skier’s thumb

42. Regular or goofy? • Regular foot = left foot forward • Goofy foot = right foot forward • Extremities toward front of board at highest risk of injury (LUE>LLE>RUE>RLE) • No asymmetry with skiing injuries

43. Snowboarding injuries • Almost ¼ of snowboarding injuries occur on the rider’s first day • Almost ½ occur during the rider’s first season • Beginners lose balance at low speed • FOOSH with wrist/distal forearm injuries

44. 4th year medical student Fell on left buttock snowboarding

45. Snowboarding injuries • Advanced snowboarders at higher risk for spine injury • Higher speed, landing a jump

46. Snowboarding injuries Most common sites of injury: 23% wrist 17% ankle 16% knee 9% head 8% shoulder 8% trunk 4% elbow 7% other

47. Upper extremity snowboarding injuries • Fractures (56%) > sprains (27%) > dislocations (10%) > contusions (6%) • Fractures: radius (esp. distal) > carpal bones (esp. scaphoid) > clavicle > humerus > ulna • Dislocations/subluxations: glenohumeral and acromioclavicular joints most common

48. Snowboarding wrist injuries • Wrist injury more common with a backward (heel side) fall – 75% of wrist dislocations • Shoulder injury more common with a forward (toe side) fall

49. Snowboarding wrist injuries • Wrist injury more common with a backward (heel side) fall – 75% of wrist dislocations • Shoulder injury more common with a forward (toe side) fall

50. 12 year old snowboarder, FOOSH